The present invention relates to a fuel detection system or identification system for an electronically controlled engine, and more particularly, to a system and method for the detection and identification of the fuel used in electronically controlled internal combustion engines. If the detected fuel is identified as an improper or unauthorized fuel, the system terminates engine operation or otherwise disables the engine.
Recent fuel developments for internal combustion engines have resulted in a number of fuel emulsions comprised essentially of a carbon-based fuel, water, and various additives. These fuel emulsions may play a key role in finding a cost-effective way for internal combustion engines including, but not limited to, compression ignition engines (i.e. diesel engines) to achieve the reduction in emissions below the mandated levels without significant modifications to the engines, fuel systems, or existing fuel delivery infrastructure.
Advantageously, fuel emulsions containing water tend to reduce or inhibit the formation of nitrogen oxides (NOx) and particulates (i.e. combination of soot and hydrocarbons) by altering the way the fuel is burned in the engine. Specifically, the fuel emulsions are burned at somewhat lower temperatures than a comparable non-aqueous fuel due to the presence of water. This, coupled with the realization that at higher peak combustion temperatures, more NOx are typically produced in the engine exhaust, one can readily understand the advantage of using water-containing fuel emulsions.
Thus, the reduction in NOx is achieved using aqueous fuels primarily because a water-containing or aqueous fuel emulsion has a lower peak combustion temperature. The actual reduction achieved, however, depends on a number of factors including the composition of the fuel emulsion (e.g. fuel to water ratio), engine control capabilities, ignition technology, engine operating conditions, etc. Moreover, having a lower peak combustion temperature does not necessarily mean that the aqueous fuel is providing less total energy or doing less work for a given mass of hydrocarbon fuel. Rather, the addition of water only requires a proportional increase in the volume of aqueous fuel emulsion to be injected in order to achieve the equivalent amount of work. However, as the volume of fuel that has to be injected increases, the engine performance considerations change. For example, the additional volume of aqueous fuel required in order to achieve the same amount of work imposes additional constraints and other design considerations in the fuel delivery systems, fuel control systems, fuel storage systems and other related systems in the internal combustion engine. Thus, where aqueous fuel emulsions are used, selected changes to the engine system must be incorporated. However, such changes are beneficial only if the aqueous fuel emulsions are actually used and are often detrimental to the operation of the engine if more conventional fuels are used.
Another problem with developing compression ignition or diesel engines to run on a fuel emulsion is that if a particular engine rating is developed, certified and sold as a fuel emulsion engine it is still capable of operating on conventional fuels such as a diesel fuel. An engine designed for a water fuel emulsion typically produces higher power and significantly higher emissions when the same volume of a conventional fuel, such as diesel fuel, is used. Unfortunately, some engine owners and operators may find an incentive to operate a fuel emulsion certified engine on diesel fuel as engine response may be faster coupled with an overall increase in power since the fuel emulsion has a significantly lower heating value than diesel fuel. Consequently, it would be advantageous if the engine could incorporate some form of protection against such fuel tampering.
It is also anticipated that various regulatory agencies may require anti-tampering devices to ensure that such an engine, certified to run on a fuel emulsions, are not run on a more conventional fuels, such as diesel fuels. In addition, for reliability and warranty related purposes, the engine manufacturer and chassis manufacturer want to ensure that diesel fuel is not used to power an engine designed for an aqueous fuel emulsion. Thus, there is a need for such fuel tampering or anti-tampering devices that can identify the fuel being used in an internal combustion engine and that disable the engine if an improper fuel is detected.
The related art fuel detection or anti-tampering systems and methods include the system and method disclosed in U.S. Pat. No. 5,701,863 (Cemenska et al.). The Cemenska et al. disclosure provides for an anti-tampering system and method that utilizes a fuel sensing device to detect physical or optical properties of a fuel, such as a fuel emulsion. Where the detected fuel is not a fuel emulsion, the engine is disabled. See also U.S. Pat. Nos. 5,186,149; 4,594,968; 4,706,630; 4,909,225, 4,974,552; 5,237,978; and 5,233,944 all which utilize physical property or optical property fuel sensors disposed within the fuel system to identify the fuel based on the alcohol content within the fuel or other fuel characteristic. Except for the Cemenska et al. reference, the related art systems are not suitable for use with a fuel emulsion. Moreover, all of the related art systems and methods require additional hardware, such as fuel sensors, which add to the cost of the engine and otherwise introduce additional reliability and maintainability concerns.
The present invention addresses the above and other needs by providing an improved method and system for the detection and identification of the fuel being used in an electronically controlled engine that is adapted to utilize a fuel emulsion. As disclosed herein, if the fuel used in the engine is identified as a fuel other than a fuel emulsion, the fuel control system restricts fuel flow to the injectors or otherwise disables the engine operation.
In one aspect, the present invention may be characterized as a fuel detection or identification system incorporating fuel identification logic within the engine control module (ECM) for preventing the use of selected fuels in an internal combustion engine, the engine being suitable for operating on a fuel emulsion. The fuel identification system includes at least one engine sensor adapted to measure a prescribed engine operating characteristic or parameter and an engine control module adapted to receive input from the engine sensor(s) corresponding to the engine operating characteristic(s). The engine control module (ECM) is particularly adapted for metering the fuel delivered to the fuel injectors of the engine based, in part on the measured engine parameter(s) and is further adapted to differentiate between a fuel emulsion and fuels other than a fuel emulsion based on said fuel quantity delivered to the engine at specified engine operating conditions. As indicated above, if the fuel used in the engine is identified as a fuel other than a fuel emulsion, the ECM or fuel control system restricts fuel flow to the fuel injectors or otherwise disables the engine operation.
Notable features of the disclosed fuel detection or identification system include the use of one or more sensors to measure the engine speed, inlet air temperature, engine oil temperature, engine coolant temperature, manifold pressure, or boost pressure, or a combination of the aforementioned engine operating parameters. Using the measured engine operating parameters, the disclosed fuel detection system differentiates between a fuel emulsion and a fuel other than a fuel emulsion based on the fuel quantity delivered at specified engine operating conditions, for example, engine idling conditions or a particular engine boost condition.
The present invention may also be characterized as a method for preventing the use of selected other fuels in an internal combustion engine adapted to use a fuel emulsion. The disclosed method includes the steps of: (a) measuring a prescribed engine operating characteristic or parameter; (b) metering a fuel delivered to the engine based, in part on the engine operating characteristic; (c) determining the fuel used in the engine based on the fuel quantity delivered to the fuel injectors at specified engine operating conditions; and (d) disabling the engine when the fuel is determined to be other than a fuel emulsion. Preferably, the engine is disabled by limiting or restricting the fuel flow to the fuel injectors of the engine.
Additional features of the disclosed method include the measuring additional engine operating parameters such as engine speed, inlet air temperature, engine oil temperature, engine coolant temperature, manifold pressure, or boost pressure, or a combination of the aforementioned engine operating parameters. Using the measured engine operating parameters, the disclosed method then determines the fuel being used based on the fuel quantity delivered at specified engine operating conditions, for example, engine idling conditions or a particular engine boost condition.